Murexide

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title: "Murexide" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["ammonium-compounds", "complexometric-indicators", "dyes", "pyrimidines", "lactams", "enones"] topic_path: "general/ammonium-compounds" source: "https://en.wikipedia.org/wiki/Murexide" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Verifiedfields = changed | verifiedrevid = 447621203 |ImageFile1=Murexide.pngclass=skin-invert |ImageSize1=230px |ImageFile2=Murexid powder.jpg |ImageSize2=80px |IUPACName=Ammonium 2,6-dioxo-5-[(2,4,6-trioxo-5-hexahydropyrimidinylidene)amino]-3H-pyrimidin-4-olate |OtherNames=Purpuric acid ammonium salt |Section1= {{Chembox Identifiers | CASNo_Ref = | CASNo=3051-09-0 | CASNo2_Ref = | CASNo2 = 6032-80-0 | CASNo2_Comment = (hydrate) | ChemSpiderID_Ref = | ChemSpiderID = 17264 | EC_number = 221-266-6 | UNII_Ref = | UNII = 4W6L62S876 | UNII2_Ref = | UNII2 = 221FEY2154 | UNII2_Comment = (hydrate) | PubChem=18275 | SMILES = [O-]\C2=C(/N=C1\C(=O)NC(=O)NC1=O)C(=O)NC(=O)N2.[NH4+] | InChI = 1/C8H5N5O6.H3N/c14-3-1(4(15)11-7(18)10-3)9-2-5(16)12-8(19)13-6(2)17;/h(H2,10,11,14,15,18)(H3,12,13,16,17,19);1H3 | InChIKey = LJYRLGOJYKPILZ-UHFFFAOYAL | StdInChI_Ref = | StdInChI = 1S/C8H5N5O6.H3N/c14-3-1(4(15)11-7(18)10-3)9-2-5(16)12-8(19)13-6(2)17;/h(H2,10,11,14,15,18)(H3,12,13,16,17,19);1H3 | StdInChIKey_Ref = | StdInChIKey = LJYRLGOJYKPILZ-UHFFFAOYSA-N |Section2= {{Chembox Properties | C = 8 | H = 8 | N = 6 | O = 6 | Appearance= | Density=1.72 g/cm3 (hydrate of ammonium salt) | MeltingPt= | BoilingPt= | Solubility= |Section3= {{Chembox Hazards | MainHazards= | FlashPt= | AutoignitionPt=

Murexide (NH4C8H4N5O6, or C8H5N5O6·NH3), also called ammonium purpurate or MX, is the ammonium salt of purpuric acid. It is a purple solid that is soluble in water. The compound was once used as an indicator reagent. Aqueous solutions are yellow at low pH, reddish-purple in weakly acidic solutions, and blue-purple in alkaline solutions.

Preparation

Murexide is prepared by treating alloxantin with ammonia to 100 °C, or by treating uramil (5-aminobarbituric acid) with mercury oxide. It may also be prepared by digesting alloxan with alcoholic ammonia.

History

Justus von Liebig and Friedrich Wöhler in Giessen, Germany, had investigated the purple product, murexide, obtained from snake excrement in the 1830s, but this was not an abundant raw material, and a method of using it as a dyestuff was not established at that time.{{citation |title= A History of the International Dyestuff Industry | author= Peter J. T. Morris |author2=Anthony S. Travis |journal=American Dyestuff Reporter |volume= 81 |number= 11 |date= November 1992 |url=http://colorantshistory.org/HistoryInternationalDyeIndustryRev1/HistoryInternationalDyestuffIndustryFirefox/dyestuffs.html |archive-url=https://web.archive.org/web/20070611123316/http://colorantshistory.org/HistoryInternationalDyeIndustryRev1/HistoryInternationalDyestuffIndustryFirefox/dyestuffs.html |url-status=usurped |archive-date=June 11, 2007

Use

Murexide is used in analytical chemistry as a complexometric indicator for complexometric titrations, most often of calcium ions, but also for copper, nickel, cobalt, thorium and rare-earth metals. It functions as a tridentate ligand.

Its use has been eclipsed by calcium-ion selective electrodes.

References

References

  1. Some information on the chemist [[Walter Noel Hartley. W. N. Hartley]] is available [http://w3.icr.com.au/~mcameron/WN%20Hartley%20&%20family.html here] {{webarchive. link. (2013-05-26 .)
  2. (2011). "The Measurement and Significance of Ionic Calcium in Milk - A review". International Journal of Dairy Technology.
  3. (1977). "Structural Studies in Metal–Purpurate Complexes. Part 1. Crystal Ctructures of Potassium Purpurate Trihydrate and Ammonium Purpurate Monohydrate (Murexide)". J. Chem. Soc., Dalton Trans..

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ammonium-compoundscomplexometric-indicatorsdyespyrimidineslactamsenones